1. Technical Field
The present invention relates to an organic electroluminescence device that has an input function. The invention further relates to an electronic apparatus that is provided with such an organic electroluminescence device.
2. Related Art
These days, there are growing expectations for the exploitation of organic electroluminescence devices to a variety of applications such as full-color display use. With the increasing expectations placed thereon, technical study and development of organic electroluminescence devices are now conducted actively. An organic electroluminescence device (i.e., apparatus) uses organic electroluminescence elements as its picture elements, that is, pixels (hereafter the term “electroluminescence” is abbreviated as “EL”). Since an organic EL element is a device (i.e., element) that is driven by an electric current, any variation or fluctuation in a driving electric current supplied thereto leads directly to the degradation of image quality. As one possible factor that could cause such variation or fluctuation in a driving electric current supplied to an organic EL element, it is conceivable that a threshold voltage gets shifted when a thin film transistor drives the organic EL element. In order to provide a technical solution to such an image quality problem, JP-A-2003-302936 discloses a method for controlling an organic EL device that achieves the reduced shift amount of a threshold voltage.
An organic EL element has a layer structure in which a pair of electrodes that is made up of a positive electrode and a negative electrode sandwiches a single-tier or multi-tier thin film that includes at least a light-emitting layer. As a typical related-art configuration thereof, a negative electrode is configured as a solid film electrode and has an electric potential that is common to all pixels in some related-art configurations, an individual, that is, separate, negative electrode is formed for each of R, G, and B three primary color components for the technical purpose of, though not necessarily limited thereto, effectively controlling a voltage that is applied to an R light-emitting layer, a G light-emitting layer, and a B light-emitting layer.
Small-sized information and electronic devices such as personal digital assistants (PDA) and personal computers have become widely used in recent years. With the increasing use of these devices, display devices having a so-called touch panel function have also come into wide use. A display device having a touch panel function allows a user to manually input instructions or the like therein; specifically, a user can make an input by contacting a touching object such as a finger, a pen, or the like, onto the display screen of such a touch-panel display device. In the technical field of touch panel display devices, a capacitive sensing scheme is known as an example of a method for detecting the contact position of a touching object such as a finger or the like, which is disclosed in, for example, JP-A-2006-146895 and JP-A-2003-196023. The capacitive sensing scheme is defined as a method for detecting the contact position of, for example, a finger or the like by means of electrostatic capacitance. When a user touches on the touch-sensitive display screen of a touch panel, electrostatic capacitance is generated. A weak electric current flows as electrostatic capacitance is generated. In the capacitive sensing scheme, the contact position of a touching object is detected on the basis of the amount of such a weak electric current that flows as electrostatic capacitance is generated. A detection electrode that is formed as a sheet and a dielectric film that is deposited on the planar (i.e., sheet-type) detection electrode are used in the capacitive sensing scheme. With such a configuration, in the capacitive sensing scheme, electrostatic capacitance is generated when a user touches on the dielectric film with their finger. It is not technically impracticable to combine a touch panel configuration conforming to the capacitive sensing scheme with an individual negative electrode configuration described above in which a separate negative electrode is formed for each of R, G, and B three primary color components.
However, in the configuration of such a touch-sensitive organic EL device that combines a touch panel configuration conforming to the capacitive sensing scheme with an individual R, G, and B negative electrode configuration described above, there is a conceivable problem of a contact position detection error due to an electric field noise. That is, since an electric field, which is generated by a driving signal that is supplied between a pair of electrodes for driving an organic EL element for light emission, undesirably reaches a detection electrode through a gap region between each two adjacent ones of the individual R, G, and B negative electrodes, the accuracy in the detection of a contact position decreases because of the electric field component that disturbs the functioning of the detection electrode as a noise.